Huda Al-Enezi

Low permeability carbonate reservoirs have been playing an increasingly important role in operators’ portfolios in the Middle East. In the Greater Burgan field of southeast Kuwait, the Mauddud is a relatively thin carbonate reservoir (20 – 60ft thickness) with low matrix permeability (0.1 – 5mD range). Under this scenario lower production performance is expected, this has been observed in practice with the Mauddud only showing good productivity when wells intercept clusters of natural fractures. In this work we describe the approach to estimate occurrence of natural fractures in the Mauddud reservoir across the Greater Burgan field, and future development scenarios.

We created a discrete fracture network (DFN) model that integrated data from several sources such as well logs, borehole images, core photos, 3D far-field sonic, 3D geomechanics and production data. Our approach was to recreate the evolution of tectonics across the Greater Burgan field to model stress perturbations around faults and predict location and characteristics of natural fractures. Borehole images, core photos and 3D far-field sonic provided hard data at well locations to calibrate the DFN, with well-level production data corroborating with results further.

Reservoir simulation models using a single porosity approach without natural fractures were not able to reproduce production results in many wells. However, results improved significantly when incorporating the DFN results into a dual permeability (DPDP) reservoir simulation model. For example, the DFN predicted intense natural fracturing in the Magwa region of the Greater Burgan field. Good production performance was observed from Mauddud completions in this area and successful simulation history matches were only obtained using a DPDP guided by the DFN. However, uncertainties in the DFN are an important action item we have identified for future work as we observed some wells with excellent production performance but modest natural fracturing from the DFN.

One way of addressing DFN uncertainty has been to incorporate horizontal multistage proppant or acid fracturing in Mauddud development wells within the next year. This has been a trend in some Middle Eastern operators as stimulation can help intercept clusters of natural fractures that do not cross the wellbore. Additional data such as higher resolution and azimuthal seismic can help narrow down uncertainties in the DFN modeling results.